The occurrence of thrombosis at the blood-polymer interface presents major difficulties in the design of artificial organs and extracorporeal devices. Advances in the development of improved biomaterials could be realized through the use of improved testing methods and through a more complete understanding of the mechanism of surface-induced thrombogenesis. We have developed a sensitive in-vivo technique to measure the transient adsorption of radio-labeled plasma proteins and platelets from flowing blood to synthetic surfaces. To date, we have used this model to study transient in-vivo thrombus-deposition on several widely used medical polymers. Each polymer has a unique protein and platelet disposition response during the 120 min. period evaluated. We propose to expand this in-vivo technique to provide needed models for evaluating polymeric materials used for vascular prostheses and to further examine the events involved in surface-induced thrombogenesis. Evaluation of transient thrombus deposition onto uncoated and protein (fibrinogen, vWf and albumin) precoated polymer surfaces on carotid-jugular shunts in monkeys will provide valuable information on blood-polymer interactions in the sub-human primate, and possible justification for the continued use of and comparisons to the canine model currently employed. Chronic studies involving implantation of iliac A-V shunts in canine subjects will allow analysis of long-term blood material interactions to be made. Evaluation of desorption and exchange of radiolabeled proteins (fibronectin, vWf, albumin, fibrinogen and alpha-2 macroglobulin) from surfaces over long-term periods, and studies to elucidate the role of certain blood plasma proteins (including transferrin, haptoglobulin, plasminogen, and ceruloplasmin) in initiating or diminishing thrombosis will provide a clearer understanding of the actual mechanism involved in vascular prostheses initiated thrombus deposition. Morphological studies of excised shunt sections using light microscopy, SEM, TEM, and HVEM in conjunction with ultrastructural labeling will be employed to determine the type and sequence of protein and WBC deposition, and to examine the spatial relationship between specific proteins and cell types. Development of a kinetic model capable of simulating specific surface thrombus deposition profiles seen in our canine experiments should lead to a greater insight into the mechanism of thrombosis and embolization on synthetic surfaces.